1. Field of the Invention
The present invention relates to an expansion valve for controlling a flow rate of a refrigerant in a first flow direction of the refrigerant and for discharging the refrigerant in a second flow direction, a heat pump type refrigeration cycle apparatus using the expansion valve, and an air handling unit having the heat pump type refrigeration cycle apparatus.
2. Description of the Related Art
Conventionally, in the heat pump type refrigeration cycle apparatus, an expansion valve is interposed between an outdoor heat exchanger and an indoor heat exchanger. In a cooling mode, a refrigerant from the outdoor heat exchanger is expanded by the expansion valve and guided to the indoor heat exchanger. In a heating mode, the refrigerant from the indoor heat exchanger is expanded by the expansion valve and guided to the outdoor heat exchanger. Various expansion valves to control the flow rate of the refrigerant for adapting to normal operation, defrosting operation, and dehumidifying operation are proposed (for example, Japanese Patent Application Unexamined Publication No. 2000-266194 and Japanese Patent Application Examined Publication No. H6-65915).
Incidentally, in many heat pump type refrigeration cycle apparatuses, the expansion valve is provided at the outdoor heat exchanger (outdoor unit) side. In this case, the refrigerant expanded by the expansion valve flows into the indoor heat exchanger via a long pipe line. Therefore, there is a problem that the expanded refrigerant is subject to pressure loss, and flow rate control by the expansion valve is difficult. The same is true in a case that the expansion valve is provided at the indoor heat exchanger side.
Accordingly, an object of the present invention is to provide an expansion valve to control the flow rate at the indoor heat exchanger in the cooling mode, and to control the flow rate at the outdoor heat exchanger in the heating mode, and a heat pump type refrigeration cycle apparatus using the expansion valve.